Introduction: (Initial Observation)
When water freezes on the surface of glass it creates a variety of different patterns of ice crystals. These patterns are often observed on the windshields of the cars where the temperature is well below the freezing point.
Every pattern of ice crystals is unique. The forms taken by ice crystals may depend on many factors, including the speed at which the water freezes, the purity of the water and the shape of the surface on which it freezes.
In this project we will investigate to see what factors affect the ice patterns.
In gathering information about this project, you can break the subject down to three simple parts.
The first part is the shape of a single crystal. I would like to know if the shape of a single crystal has any thing to do with the shape of a molecule. Note that at this time you are not restricting your study to water. Any crystal of any substance may have a shape affected by the molecular structure of that substance. To search the Internet, I used the keywords (crystal shape + molecule) and I found the following links:
The gathered information shows that the shape of a crystal is a function of the shape of the molecule. That does not mean that the shape of a crystal is the same shape as a molecule, but they are related.
The second part is the mechanism of crystallization. Crystals may be formed from liquids, gaseous or vapors. Snow crystals, for example, are made of water vapors. Water crystals may also form on a car’s windshield in the winter by the moisture of the air. To find some information about this form of crystallization, I searched the Internet for (crystal+vapor).
The results showed that making crystals from vapors is not just limited to the nature and has industrial use as well. I am wondering if the shape of a single crystal has anything to do with the method of crystallization. I would like to know if a single crystal made from vapor is the same shape as a single crystal made from liquid. Following are some related links.
The third part is how do crystals, bound to each other, make certain patterns. I would like to know what factors affect the patterns. I searched the Internet for (crystal + pattern) or Ice pattern. This search did not give me much technical results, but I found some nice ice patterns like this:
Read books, magazines or ask professionals who might know in order to learn about water crystals. Keep track of where you got your information from. Following are some related Internet links.
|Crystal is a solid substance with orderly configured atoms and molecules. Crystals can be seen in snow, crystallized quartz, diamonds and table salt.
For example, in snow there are no crystals that have the same “face” (as is true with people’s faces). If the water around the world started out with the same structure then probably all the snowflakes could have the same crystal structure.
Mr. Masaru Emoto in Japan had a theory that when water molecules crystallize, pure water becomes pure crystal, but contaminated water may not crystallize as beautifully. In 1994, he started his experiments of photographing the crystals of different waters. He succeeded in the end to take photos of spring water, rain water, and lakes all around the world. When he looked at the crystal pictures, the most important thing that he noticed is that the water tried to form a complete “hexagonal crystal structure”.
From experiments he learned that the chipping away and/or collapsing of crystal structure were not good signs. He felt that the water showed different “faces of water”. The water is trying very hard to be a “clear water” (a beautiful looking crystal). Regretfully, it is a known fact that chlorine and other chemical substances added to water for purifying purposes are not good for the body, but nevertheless most people in the industrial countries drink such water.
|Mr. Emoto discovered that tap water and contaminated water (urban rivers, lakes, etc.) couldn’t form a full hexagonal structure. Some of the urban waters showed twisted, very deformed crystals. Therefore, we wanted to see the different crystal pictures from tap water and when we added coral into that water and this is the results:|
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement. This is sample question:
How does the freezing temperature affect the ice patterns on glass? Elements of ice patterns include the shape of ice crystals, the size of ice crystals, and the collective positioning of micro crystals in relation to each other.
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
Factors that may affect the shape of ice crystals are:
- The source of iced water (dew, rain)
- The weather temperature
- The speed that temperature drops
This is a sample on how you define variables when you are testing the effect of temperature on ice patterns:
Independent variable (also known as manipulated variable) is the freezing temperature.
Dependent variables (also known as responding variable) is the ice pattern
Constants are the type of water and the type of freezing surface.
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. This is a sample hypothesis:
My hypothesis is that very fast crystallization can create needle shape crystals in straight lines or branched lines.
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
In order to perform experiments on creating ice patterns, we need a cold glass surface that can be used for these experiments. In our experiment we will create such a cold glass surface. For the best results to create a very cold temperature, liquid nitrogen or solid carbon dioxide (dry ice) can be used, but in this experiment we use saltwater to create low temperatures.
Water that creates these patterns is rain and dew. We also need a method to simulate rain and dew.
In this experiment we will use ice to create a freezing temperature. Mixing salt with ice will reduce the melting point of ice and drops the temperature to -5º C. We could also use antifreeze or alcohol instead of salt, but we choose salt because it is more environmental friendly. Steps of the experiment are as follows:
- Fill up a plastic container with crushed ice
- Pour lots of table salt over the ice to completely cover the ice.
- As the ice starts to melt, stir it to accelerate the melting process. This will make the mixture of ice-water-salt much cooler.
- Use a thermometer to check the temperature of the mixture.
- If the temperature is below -10ºC you can start the next step.
- Pour some of this cold water into a clear glass container.
- Observe the sides of the glass container for ice patterns caused by moisture in the air.
- Take pictures or make drawings of the ice patterns on the glass.
- Make notes of the conditions that created that ice pattern. (Mixture temperature, outside temperature, source and type of frozen water; after how long ice patterns were created?)
Note: If you need lower temperatures, you may use dry ice instead of regular ice and salt. Dry ice is frozen carbon dioxide. The temperature of dry ice is -109.3°F or -78.5°C. By placing a layer of insulating materials such as paper, cloth, cardboard and felt between the dry ice and a piece of glass you can form different temperatures at the glass surface. Attach your thermometer bulb to the surface of glass using zinc oxide ointment or any heat conductive paste.
Repeat the above experiment at different mixture temperatures. Observe the ice patterns that form on the outside of the glass container. When the mixture temperature is lower, ice will crystallize faster and that can affect the ice patterns.
Need a control?
Place another cup of tap water away from your experiment setup and do nothing with that. This will assure you that the formation of ice patterns on your experimental cup is due to the low temperatures.
Repeat the experiment 1 at a very low temperature, but spray different types of water to the outside of the super cold glass container. (Tap water, distilled water, slightly carbonated water, slightly acidic water.)
- For acidic water, add about 10% vinegar to distilled water.
- For carbonated water add a about 10% carbonated water to distilled water.
- You may also try oxygenated water by adding 10% Hydrogen Peroxide to distilled water.
- Distilled water can be purchased from pharmacies.
- The reason that we test carbonated, oxygenated and acidic waters is that similar material can exist in atmosphere and get to the earth in the form of rain and dew.
- You could also use a glass container instead of a plastic container. In this way ice patterns would create on the outside of the glass container.
- This experiment must be performed in a cold and dry environment with minimum possible humidity. Otherwise the amount of moisture condensed on the surface of glass will be too much and that can potentially stop any ice from forming.
Alternative Experiment method:
Ice pattern experiments using petri-dishes and a refrigerator
In this experiment we use the freezer shelf of a refrigerator as a source of freezing temperature. For glass surface we use glass petri dishes (or plastic petri-dishes).
- Set the refrigerator at its coldest temperature and leave it at that setting for at least one hour.
- Place a thermometer in the freezer for one minute and then read and record the temperature. Wear gloves so your hand temperature does not affect your results.
- Wet the bottom of a petri-dish with a few drops of water, place the lid, write the temperature on the lid and place the petri dish with the lid in the freezer.
- After 30 minutes inspect the ice crystals using a magnifier and record your observations.
- Slightly reduce the temperature of your refrigerator/freezer so it will be about 3 to 5 degrees warmer. Repeat the steps 2 to 4 with this new temperature and other temperatures that you can produce. Try to test at least 5 different freezing temperatures. The ideal temperatures for this experiment are -2ºC, -5ºC, -8ºC, -11ºC, -15ºC, -18ºC, -21ºC; however, it might be hard to get to the right temperature every time. Work with temperatures that are available to you.,
Your results table may look like this:
|Freezing Temperature||Ice patterns|
Need a graph?
The results of this project do not require a graph. They can be expressed in a few sentences or a table.
If you really need to have a graph, make a bar graph. The height of each bar will show one of the temperatures that you tested. The name of bar or an image above each bar will indicate the type of crystal (or ice pattern) that forms in that temperature.
Materials and Equipment:
Can be extracted from the experiment section. This is a sample:
- Table salt
- Crushed ice or ice cubes
- Plastic container
- Glass cup or beaker
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
No calculation is required for this project.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
I completed the experiment and need to make a graph. My teacher wants a line graph for it. If a line graph is not possible, please help me make a bar graph as your site suggests.
Data for unsalted water:
Freezing Temperature Ice patterns
-1ºC Tiny dots located far from each other
-4ºC Small needles
-8ºC Long needles
-11ºC Tiny dots very close to each other
Data for salted water:
Freezing Temperature Ice patterns
-1ºC No ice
-4ºC No ice
-8ºC Very thin long needles
-11ºC Fernlike bushy shape
This project does not really need a graph. Graphs must provide a simple to understand visual presentation of your results; while in this case a graph will not be simple to understand. In either case this is a sample graph for your experiment with unsalted water.